a-ak a-ok aaaa aaab aaar aaav aaba aabb aaka aaoo aara aaro aava abaa abab abak abar abb- abba abbb abbo abbr aboa abob abok aboo abor abov abra abro abva akaa akao akar akka akko akok akr- akra aoba aora aorb arab arak arar arba arka arko aroa arob aroo aror arr- arra arrk arro arrr arva arvo avab avao avar avor avra avro avva avvo baaa baak baar baba babb babo babr bak- baka bako bakr bar- bara barb bark baro barr bava bbbb boab boak boar boba bobb bobo boka boko boob book boor bor- bora bork boro borr bova bovo brab brak brao brav brka brkb broa brob brok broo bror brrr kaaa kaab kaak kaar kaba kabb kabo kabr kaka kakk kako kaoa kaok kaor kara karb kark karo karr karv kava kavb kavo kavv kbaa kbab kbak kbar kbba kbbb kbbk kbbo kbbr kbkb kbkk kbko kbkr kbkv kboa kbob kbok kboo kbov kbra kbrb kbrk kbro kbrv kbva kbvb kbvo kbvr kkaa kkar kkba kkbb kkbo kkbr kkkk kkoa kkob kkoo kkor kkov kkrb kkrk kkro kkrr kkrv kkvr kkvv koab koak koar koba kobb kobk kobo kobr koka kokb kokk koko kokr koob kook kooo koor koov kora korb kork koro korr korv kova kovk kovo kovr krab krak krar krav krba krbb krbk krbr krka krkk krko krkr krkv kroa krob krok kroo kror krov krrb krrk krro krrr krva krvb krvk krvo krvr krvv kvab kvak kvar kvbr kvoa kvob kvok kvoo kvor kvov kvra kvro kvrr kvrv kvvr kvvv oara obak obba obbo obkb obok obor obra obro okak okka okko okok okor okra okro ooaa ooak ooba oooo oora orab orak orao orar orav orba orbb orbo orka orko oro- orok oror orra orro orvr ovar ovo- ovoo ovra raab raak raba rabb rabk rabo raka rakk raob raok rara rarb rark raro rava rbbb rbbr roab roak roar rob- roba robb robo roka rokk roko rokr roob rook roor rora rork roro rova rovo rrrr vaar vaka vara vark varr vava vkor voar voka voor vor- vora voro vovk vrak vrav vrba vvob vvvv